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I do have a server with 2 CPUs (22 Cores each plus HT). I created a KVM Guest with 64 allocated cores. When I run a compilation task the virtual machine shows all 64 cores at 100% (at moderate Disk I/O and memory usage) but on the physical machine the guest only uses 14 cores at 100% instead of all the 88 cores randomly (or 64 dedicated cores at 100%). Even if I spawn more compilation tasks this doesn't change. Is there any parameter or setting I have to change to actually use all the computing power that is available?

EDIT: screenshot of htop (left guest, right host)

  • How do you create your KVM Guest? CLI? GUI? – Lenniey Feb 17 '17 at 9:03
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    I used an XML-Dump in virsh because it was a migration from an older server and changed configuration to match the new server in virt-manager. – HibikiTaisuna Feb 17 '17 at 9:17
  • Could you show the output of virsh cpu-stats <VMname>? – Lenniey Feb 17 '17 at 9:53
  • All cores except of the 14 show 0.0000s. But I could find at least one error. There was a vCPU pinning in the XML which doesn't appear in virt-manager -.- I removed it via for i in {0..63}; do sudo virsh vcpupin $kvmdomain $i r --config; done and restarted the guest. Unfortunately it still uses only the 14 cores. I will reboot the host to see if it still happens. – HibikiTaisuna Feb 17 '17 at 10:10
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There was a vCPU pinning in the XML which doesn't appear in virt-manager -.- I removed it via

for i in {0..63}; do sudo virsh vcpupin $kvmdomain $i r --config; done 

and removed the line in the XML-file via

sudo virsh edit <domain> 

After that I restarted the guest.

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    And now it works, yes? – Lenniey Feb 17 '17 at 12:20
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    Until the comment by @Lenniey has been handled, this is not an answer to the question. – pipe Feb 17 '17 at 13:42
  • @Lenniey yes, now it works as intended – HibikiTaisuna Feb 22 '17 at 15:00

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